What color was a T. Rex? -Jack H., 7, Taunton, England

When we dig up fossils from the Earth they can tell us a lot about life in the past.

Fossils are preserved traces of plants and animals. Unfortunately, one thing that fossils don’t tell us a whole lot about is dinosaur color. This includes the color of Tyrannosaurus rex.

In fact, most of the dinosaur fossils we’ve found are of teeth and bones. We’ve only found traces of dinosaur skin a couple of times.

That’s what I learned from my friend Gary Webster at Washington State University. He’s a paleontologist fascinated with the fossils of colorful sea creatures that have tentacle arms. Called crinoids, they live in the ocean today and also lived in dinosaur times.

Since we can’t observe dinosaurs, some scientists look to the colors of their cold-blooded cousins in the reptile family, including snakes, turtles, and lizards. Other scientists are gathering evidence that leads them to believe dinosaurs might have had some kind of feathers. They think dinosaurs may have evolved into some of my most favorite animals: birds.

Webster told me about a field trip he took a few years ago to China, where a woman found a small dinosaur fossil with what looked like feathers. The dinosaur was probably about the size of a chicken.

Another dinosaur found in China that we’ve learned about in recent years was a small predator called Sinosauropteryx.

Scientists can actually look at tiny little elements in fossils to learn about animal fur, feathers, and skin. These tiny structures are called melanosomes. Melanosomes can be found in animal cells and they absorb light in different ways that make the colors we see. The different shapes of the melanosomes can sometimes tell us different things about a species’ coloring.

Researchers who studied the patterns of these melanosomes in Sinosauropteryx found that the predator likely had a reddish-brown and striped tail. It had tiny feathers they called “dino fuzz,” too. It’s one clue to one dinosaur color.

Other clues may come from what we know about a dinosaur’s daily life. Dinosaurs lived during the day, which made them diurnal animals. Diurnal animals, including reptiles and birds, use color to “talk” to one another. Wearing bright colors can help attract mates or keep predators away.

Color can also help animals blend into their environments. There’s a chance that plant-eating dinosaurs that lived among the trees might have had a greener color. Predators out in the grasslands may have been brownish. But we don’t know for certain, and scientists are looking for answers.

“With discoveries up in Canada with some traces of skin and what’s coming from China, ultimately we should get some more information about colors,” he said.

We may never know what sounds T. rex made, how they used their tiny arms, or their exact colors. But in the meantime, we’ll keep digging.